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Патент USA US2405188

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Aug. 6, 1946. '
H.
2,405,188
CAMPBELL ‘
CONTROL SYSTEM FOR ROTATIVE WINGED AIRCRAFT
Filed July 5, 1941
2 Sheets-Sheet 1
Aug. 6, 1946.
H.- s. CAMPBELL
2,405,188
‘CONTROL SYSTEM FOR- ROTATIVE WINGED AIRCRAFT
Filed July- 51941
2 Sheets-Sheet z
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laatentecl Aug. 6, 1946
2,405,188
UNITED STATES PATENT‘ OFFICE
2,405,188
CONTROL SYSTEM FOR ROTATIVE WINGED
AIRCRAF
Harris S. Campbell, Bryn Athyn, Pa., assignor to
Autogiro Company of America, Philadelphia,
Pa., a corporation of Delaware
Application July 5, 1941; Serial No. 401,156
12 Claims. (01. 244-47)
1
2
This invention relates to a control system for
rotative winged aircraft. The invention is con
cerned with that general class of control systems
in which the sustaining rotor itself is employed
hand of the pilot during an aerodynamically in
duced displacement of the rotor beyond said
limited range. This limited range of movement
of the controls independent of the servomotor is
for control‘purposes.
also advantageous in eliminating “hunting” un
In aircraft of this type, the sustaining rotor (or
der the influence of the action of the servomotor.
rotors) is either mounted for tilting movement as
Excessive wear of the parts is thus also reduced.
a whole or is arranged so that the blades of the
How theforegoing and other objects and ad
rotor are capable of pitch variation, the control
vantages are attained will be apparent to those
moment, in either case, resulting from shift of 10 skilled in the art from the following description,
the lift line of the rotor with respect to the center
referring to the accompanying drawings, in
of gravity of the aircraft. Such rotor control is
employed principally as a ?ight control deter
Figure 1 is a side elevational view of portions of
mining the ?ight attitude of the aircraft. The
a rotor mount, rotor hub and blade, with the con
invention is applicable to aircraft having rotor 15 trol system of the present invention applied
control whether the rotor is normally aerodynam
thereto;
.
'
ically actuated in flight, or is normally mechani
Figure 2 is a sectional view of a ?uid pressure
which—
cally driven in ?ight.
.
One of the primary objects of the invention'is
the provision of a control system incorporating 20
power means arranged to relieve the pilot of a
portion of the rotor loads and reduce the effort
required in maneuvering. At the same time the
invention has in view retaining control “feel,” by
arrangement of the control system so as to per
mit a portion of the rotor loads to be transmitted
to the manually operable member, such as a joy
.
'
control valve employed in the system of Figure 1;
and
‘
'
'
'
.
'
Figure 3 is a view of certain parts shown in
Figure 1 but with a modi?ed control system ap
plied.
'
As herein illustrated, the invention is shown as
applied to a sustaining rotor having a hub which
is pivoted for tilting movement in all directions
for control purposes. Thus, the hub 4 is pivotally
mounted by trunnions 5 within a ring 6, which
stick.
ring is, in turn, .pivotally mounted on trunnions
Both of the points mentioned in‘the preceding
l'—'! in a ?xed frame 8—8 supported at the top of
paragraph (relieving the pilot of loads, and re 30 a pylon structure 9-!0. Trunnions 5 provide an
taining “feel”) are of substantial importance
axis for tilting the hub and thus the rotor as a
because of the very fact that the rotor which is
used as the medium of control constitutes the pri
whole in a fore and aft direction, while trunnions
mary or sole means of sustension for the aircraft.
provide for tilting of the rotor to one side or the
'i--1, being disposed fore and aft of the aircraft,
While the invention may advantageously be used 35 other. A rotor control of this general type is ful
in any rotative winged aircraft having rotor con
ly disclosed in copending application of Juan de
trol, because of the considerations just men
la Cierva, Serial No. 645,985, ?led December 6,
tioned it is especially useful in rotative winged
1932.
aircraft of relatively large size or in which heavy
The root end of a blade appears at H, the
rotor loads would otherwise be imposed on the 40 same being coupled by a “drag” pivot l2 with
control system. '
.
an extension link l3 which, in turn, is connected
Another object of the invention is the provi
with the hub lugs I4 by means of a “?apping”
sion of a servo control system, retaining “feel,”
pivot l5. While only one blade is shown it will
which is further capable of direct manual opera
be understood that the rotor preferably incor
tion in the event of failure of the servomotor, and
porates a plurality of such blades. Provision may
this without the necessity for any alteration of
be made for driving‘the rotor, as by a drive
the mechanism.
.
shaft l6 connected with gearing housed at IT.
in accordance with another aspect of the in
Although the rotor here shown is of the type
vention, provision is made for a limited range of
adapted for aerodynamic or autorotational ac
purely manual control before the operation of the 50 tuation
normal ?ight, the drive mechanism
may be employed for initiating rotation of the
servomotor is initiated. The control is, therefore,
keenly sensitive to aerodynamically induced dis
rotor on the ground prior to take-off in the man
placements of the rotor, the pilot being imme
ner disclosed, for example, in copending appli
diately apprised of any such displacement with
cation of Juan de la Cierva, Serial No. ‘738,349,
out, however, imposing heavy control loads on the
?led August 3, 1934, now'Patent No. 2,380,583,
amiss
,
4
3
issued July 31, 1945. At some convenient point in
the rotor drive system, for example, in the shaft
ing it, a manually operable clutch is interposed
and, in addition, to ensure free rotation of the
rotor in normal ?ight an overrunning clutch is
desirably interposed between the rotor drive gear
ing housed at H and the rotative hub spindle
ton 4'l—-li8 working therein, the piston heads be
ing interconnected by a stem 48 and having a
piston rod 50 projecting from one end of the
cylinder for connection with lever 2i as at 5|
(see Figure 1) . Cylinder 46 is pivotally connected
at 460: with push-pull element l9.’
From Figure 2 it will be noted that the pres
sure pipe 44 communicates with cylinder 45 in
itself.
termediate the two piston heads 41-48. Pipes
In considering the control system, it is ?rst
pointed out that in accordance with the inven 10 52 and 53, also communicating with the cyl
inder 46, are extended respectively to the lower
tion provision is preferably made for employ
and upper cylinders 30 and 29 of the servomotor.
ment of a duplicate set of various of the control
A passage 54 formed at one side of the control
parts hereinafter described, one set being ar
valve cylinder 56 is placed in communication with
ranged in the manner illustrated for the pur
pose of controlling the tilting of the rotor about 15 opposite ends of the cylinder through ports 55
and 56, passage 54 also being coupled by pipe
the transverse axis of trunnions 5, and the other
57 with the ?uid reservoir 33 (see Figure 1).
set being employed for lateral tilt of the rotor,
From the foregoing description of the servo
this latter set not being illustrated.
A control arm I8 projects rearwardly from
motor and its control valve, it will be seen that
housing H, and to this arm there is connected 20 movement of the pilot’s control stick 25, for ex
ample, forwardly, will raise point 220: on lever 2|
a push-pull element I9, the connection 20 de
about point 23a as a fulcrum, thereby moving
sirably taking the form of a universal or ball
stem 50 of the control valve upwardly and plac
coupling so as to accommodate lateral tilting of
ing pipes 634 and 52 into communication with
the rotor about the axis of trunnions 'I—-'l. At
its lower end push-pull element 19 is pivoted 25 each other in the space between the ‘two piston
at We to a beam or lever 21. This lever is
adapted to be moved upwardly or downwardly
heads of the control valve, and at the same time
by a push-pull tube 22 and also by piston rod 23
which are connected with the lever at opposite
line 51. This results in admission of pressure to
the lower end of the servomotor cylinder 30, and
ends, at'22a and 23a, respectively.
placing pipe 53 in communication with return
Push-pull 80 exhaust of pressure from the upper end of servo
motor cylinder 29, thereby effecting upward move~
merit of piston rod 23 of the servomotor. After
a given displacement of the pilot’s control stick
ment at 26. Pivot 26 is carried by an arm 21
25, point 22a on lever 2| is maintained substan
depending from rockshaft 28 which latter, as 35 tially ?xed, so that the upward movement of
piston rod 23 not only actuates the rotor control
will be understood by those skilled in the art,
tube 22 extends downwardly for attachment at
24 with the pilot’s control stick or member 25
which is pivotally mounted for fore and aft move
is adapted for connection with a lateral rotor
control, actuable by movement of the control
element l9 but also causes the lever 2| to move
angularly in a direction to withdraw stem 50
from the control valve 45 and thus bring the pis
stick from side to side, and which may conven
iently be coupled to ring 6 of the rotor mount.
40 tons 4‘! and 48 back to the mid position shown
The ends of piston rod 23 project respectively
in full lines in Figure 2, in which position the
into upper and lower ?uid pressure cylinders 29
pressure line 45 and the return line 51 are out
off from the servomotor cylinders. The adjusted
and 35, and the ends are equipped with pis
position of the control system is thereby main
tons 3!. The cylinder and piston devices 29, 30,‘
3| constitute a servomotor for applying a con 45 tained until a new adjustment is made by the
pilot.
trolling force to the rotor control element 19.
The ‘cylinders 29 and 38‘ are mounted by bracket
A similar but inverted action takes place upon
32 on the rotor support or pylon it, which thus
movement of the pilot’s control stick 25 in the
constitutes a ?xed reaction base to, which a
opposite direction.
50
It will be understood that various of the fluid
portion of the rotor loads is transmitted.
The fluid pressure supply and control for the
pressure connections, such as those indicated at
servomotor are as follows:
44, 52, 53 and 51 are ?exible so as to accom
'
A fluid reservoir (oil preferably being used) is
modate the movement of the control valve de
shown at 33. The reservoir supplies oil to the
scribed.
intake sides of pumps 34 and 35 through pipes 35, 55 The structure and operation above described
are of particular advantage for several reasons,
31 and 38. Pump 34 is geared or otherwise
driven from the rotative part of the hub, while
as follows:‘
pump 35 is similarly adapted to be driven from
In the ?rst place, it will be observed that point
the aircraft engine (not shown). The discharge
lSa, on beam 2! is located closer to point 23a
or pressure connections 39 and 40 of the two 60 than is point 22a. In consequence of this, aero
dynamically induced loads coming down from the
pumps are provided withv check valves 4! and 42
rotor through push-pull element H! are carried
and deliver into a ?tting 43 from which ‘a pipe
M transmits the pressure to the control valve in
dicated generally at 45.
'
’
/ in'large part through the servomotor to the ?xed
reaction base thereof, such as the pylon member
Two sources of pressure, 1. e., the two pumps 65 It, only a minor fraction (for example, one
34 and 35, are employed in order to positively
assure availabil-ityof ?uid pressure for opera
quarter) of such loads being transmitted through
the push-pull member 22 to the pilot’s‘ control
stick 25.‘ In this way the forces transmitted to
tion of the control system under all conditions.
Thus, failure of the engine will not impair the
the pilot’s hand are greatly reduced, while at the
supply, nor will ‘failure of either of the pumps. 70 same time the “feel” of the rotor is retained.
When the ‘control is actuated by the pilot, only
Check valves 4| and 42 prevent loss of pressure
a minor fraction of the required control force
produced by one pump in the event of failure of
need be supplied by the pilot’s hand, the balance
the ‘other, or when the other is not operating.
of the force (about three-quarters, in the exam
As seen in Figure 2, the control valve 45 con
sists of a cylinder 55 with a‘ double headed pise. 75 ple given) being supplied by the se‘rvomotorl
2,465,188
.
.
5
.
Since the axial dimension ‘of pistons 41' and
therefrom to contacts 19‘ and 90 disposed in
‘48 0f the control valve 45 is somewhat greater
spaced relation one above and the other below
than the corresponding dimension‘ of the ports
through which pipes 52 and 53 communicate with
cylinder 48, a limited range of movement be
tween the piston stem 50 and the cylinder 45 is
provided before operation of the servomotor is
initiated. “Hunting” and consequent excessive
the lever 2!. .Thus, upon angular movement of
wear of the parts are thereby avoided and, in ad
lever 21, one or the other of the motor circuits is
completed (through “ground”), so as to provide
for rotation of the motor in one direction or the
other.
Operation of the arrangement of Figure 3 is
similar to that described above. Upon displace
dition, within the intermediate limited range just 10 ment of the pilot’s control wheel 58 in an axial di
rection, the worm unit 64 is actuated so as to
mentioned, the pilot’s control is highly sensitive to
move push-pullmember 61 upwardly or down
any displacements of the rotor which may be set
wardly, thus making contact at 19 or an and ini
up as a result of wind gusts or other irregular
tiating operation of the reversible motor in the
?ight conditions. In the event of a substantial
rotor displacement in any direction, after the 15 correct sense to effect the desired control. As
before, the major portion of the rotor loads is
slight initial control stick movement permitted by
transmitted to a ?xed reaction base, although, at
said limited intermediate range, the servomotor
the same time, the “feel” of the controls is re
tained.
to oppose the displacement of the rotor.
I claim:
It is also to be observed that the servomotor 20
will automatically come into operation in a sense
and the operating connections between the pilot’s
control member and the rotor are arranged so
that in case of failure of the servomotor, manual
operation of the control system will not be im
1. In an aircraft having a sustaining rotor con
stituting the principal lifting means for the craft,
and a rotor mounting pylon adapted to carry the
loads between the craft and the rotor, a control
paired. In this event, the range of movement of 25 system operative on said rotor to shift the lift line
thereof whereby to control the attitude of the air
the pilot’s control stick for a given rotor displace;
craft in ?ight, said control system including a
ment will be substantially greater than with the
rotor control element subject to rotor loads and
servomotor operating, but the pilot will still have
movable under the in?uence thereof, a pilot’s con
available manual control which is adequate for
30 trol member, reversible operating connections be
safe operation or landing.
tween said member and said element, a servo-~
The arrangement of the rotor and rotor mount
motor coupled with said connections and with
as shown in the modi?cation of Figure 3 is simi
said pylon as a ?xed reaction base and providing
lar to that of Figure 1. In Figure 3, however, a
a control force for supplementing that applied to
different type of pilot’s control member is em
ployed, i. e., a hand wheel 58 which may be 35 the control member by the pilot, and control
means for the servomotor actuable by manual
mounted in the general manner disclosed in co
movement of said operating connections, the
pending application of Agnew E. Larsen, Serial
servomotor and pylon assuming a portion of the
No. 209,511, ?led May 23, 1938, now Patent No.
rotor loads, the remainder being carried by said
2,273,051 issued February 17, 1942. Thus, the
wheel has an axis member 59 which is adapted for 40 operating connections to the pilot’s control mem
ber.
axial movement as well as rotation, the axial
2. A construction in accordance with claim 1
:movement being transmissible to a closed circuit
in which the operating connections include a lever
‘cable 50 passing over appropriate guide pulleys 6i
connected with the rotor control element, with
:and incorporating a length of chain 62 adapted
:to engage a sprocket mounted on a worm shaft 63 45 the pilot’s control member and with‘ a movable
‘extended into worm unit 64. This unit comprises
:a worm (not shown) mounted on shaft 63, and a
cooperating worm wheel connected with shaft 65,
‘which shaft also carries arm 66 for actuating
part of the servomotor, the three points of con
nection being geometrically disposed to provide
mechanical advantage for the pilot in 'making
manual adjustments, whereby the servomotor
push-pull member 61. The Worm unit, though 50 supplies more than half of the total control force
required for a given displacement and more than
preferably providing some mechanical advantage
:for the pilot, is designed for reverse transmission ' half of the control reaction loads are taken by
the pylon when said motor goes into operation.
{of forces therethrough, as in said copending ap
3. An aircraft sustaining rotor control system
plication of Agnew E. Larsen. It will also be un
derstood that another cable system including a 55 including a rotor control element subject to rotor
loads and movable under the in?uence thereof, a
worm unit may be associated with hand wheel 58
pilot’s control member, mechanism interconnect
for actuation by rotation of said hand wheel, as
ing said element and said member including a
in said copending Larsen application.
servomotor arranged to assume a portion only of
The servomotor of Figure 3 takes a different
the rotor loads, the remainder of said loads being
form than that shown in Figure 1. In Figure 3
carried by said mechanism to the pilot’s control
a rotative reversible electric motor 88 is mounted
member, and means whereby said servomotor de
on the pylon member It by a bracket 69, the mo
rives power from the rotor upon which it acts.
tor being connected with threaded rod 10 through
reduction gearing housed at 1 l . A threaded block
4. In an aircraft having a sustaining rotor con
12 cooperates with rod ‘Hi and is connected with 65 stituting the principal lifting means for the craft,
a control system operative on said rotor to shift
lever 2! by a pivot 72a, The opposite end of lever
the lift line thereof whereby to control the at
2| is coupled with push-pull member 6'! as at 61a
titude of the aircraft in ?ight, said control system
and the rotor control element ‘i3 is coupled with
including a ?uid pressure actuable servomotor,
the lever as at 13c.
‘
A source of current for operating the motor 70 a ?uid pressure pump driven by the rotor and
adapted to supply ?uid pressure for operation of
68 is indicated diagrammatically at 14, the same
said motor, and a ?uid pressure pump driven ‘by
being grounded through connection 15. Wire 16
the aircraft engine and also adapted to supply
couples the opposite side of the current source
?uid pressure for operation of said motor.
with the motor, and for reverse operation of the
5. In an aircraft having a sustaining rotor con
motor the two connections ‘I’! and 18 extend 75
7
8
stituting the principal lifting means for the, craft,
energy to the servomotoris the rotor, and in
which a coadjuvant power source driven from
a control system operative on said rotor to shift
the aircraft engine is also connected to supply
the lift line thereof whereby to control the at
driving energy to the servomotor.
titude of the aircraft in ?ight, said control sys
10. In an aircraft having sustaining rotor
tem including a rotor control element movable in 5
means constituting its principal lifting agency,
each of two opposite directions and subject to
a control system operative on said rotor means
rotor loads, said element being movable under’the
to shift the lift line thereof whereby to control
in?uence of said loads, a servomotor for moving
the attitude of the aircraft in ?ight, said control
said element in either of said two opposite direc
tions comprising a reversible'rotative motor one 10 system including a ?uid pressure actuable servo
part of which is mounted on a relatively ?xed
motor, a ?uid pressure pump driven from the
rotor means and adapted to supply ?uid pressure
reaction base, ‘a screw rotatable by said motor, a
threaded block associated with said screw and
movable axially of the screw upon rotation of the
latter, a lever interconnecting the rotor control
element and said block, a pilot’s control member
movable in either of two opposite directions, re
for operation of said‘ motor, and a ?uid pressure
pump driven by the aircraft engine and also
adapted to supply ?uid pressure for operation of
said motor, together with a pilot’s control element
in the body of the craft having control connec
tions adapted to monitor the operation of said
motor, and connected to receive at least a por
tion of the rotor thrusts.
11. In an aircraft having main sustaining rotor
versible operating connections between the pilot’s
control member and said lever, and control means
for the servomotor associated with said lever and
actuable upon angular movement thereof in one
direction or the other to initiate operation of said
means, power means for rotating said rotor means,
and mounting structure for the rotor means in
motor in one direction or the other.
6. A construction according to claim 3, together
cluding an aircraft body and rotor mounting
with a, rotor mount on which the servomotor is 25 means extending therefrom, the combination of:
supported close to the rotor, whereby the trans
a control connection subject to rotor loads and
mission of power to the motor is shortened while
movable under the in?uence thereof and opera
at the same time the rotor load reaction on the
tive to shift the lift line of the rotor means
servomotor is taken by said rotor mount.
whereby to control the craft in ?ight; and a con
'7. In a rotary-wing aircraft comprising a fuse
30 trol system, including motor means coupled to
lage and a rotor tiltable with respect thereto,
mechanism for tilting the rotor which includes in
combination: a rigid pylon structure for mount
ing the rotor uponthe body of the craft and serv
react between said connection and the mounting
structure to apply a control force to the former
and to react against the latter; a pilot's control
member in the craft; and a motor control linkage
ing also as a machinery base; a servomotor .
mounted on said pylon as a base, and having a
part which moves in a direction lengthwise of the
pylon when the motor is actuated; a ?oating lever
having one end pivotally connected to said motor
part; a reversible connection from the rotor piv
otally connected to the ?oating lever adjacent
the motor end thereof; a control member in the
fuselage having a reversible connection pivotally
coupled to the other end of the ?oating lever;
a power source connected to deliver driving energy
to the servomotor; and a monitor device govern
ing the flow of energy to the motor and mounted
for actuation by the ?oating lever upon move
ment of said lever beyond a limited idle range,
whereby said motor is actuated upon substantial
aerodynamic displacements of the rotor to cor
coupled to said pilot’s control member, said link
age also being coupled to transmit a portion of
the rotor loads between said connection and said
pilot’s control member, elements of said control
system including said linkage being constructed
to be operative upon the rotor means whether or
not the power means for rotating said rotor means
is in operation.
712. In an aircraft, sustaining rotor means con
stituting the principal lifting agency, power
drive means for said rotor means, a disconnect
ing device between said two means whereby the
rotor means may autorotate upon power discon
nection or failure, and a control system operative
on said rotor means to shift the lift line thereof
an whereby to control the attitude of the aircraft in
?ight, said control system including a ?uid-pres
rect the same, as well as upon normal displace
sure-actuable servomotor, a ?uid pressure pump
ments of the control member to effect the purpose
drivenby the rotor and adapted to supply ?uid
thereof, and in either case the major control
loads are carried by the rotor mounting plyon.
8. The combination set forth in claim 7 in
pressure for operation of said motor, and a ?uid
pressure pump driven from the aircraft engine in
which the power source connected to deliver driv
dependently of the position of said disconnecting
device, said last named pump being also adapted
ing energy to the servomotor is the rotor.
to supply ?uid pressure for operation of said
9. The combination set forth in claim 7 in which
motor.
the power source connected to deliver driving .60
HARRIS S. CAMPBELL.
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